1. Field of the Invention
The present invention relates to a communication light detecting structure capable of enabling the user to visually check the state of communication in a communication optical fiber, a communication light detecting optical connector including the communication light detecting structure, and a communication light detecting optical cable including the communication light detecting structure.
2. Description of the Related Art
In optical communication related facilities, such as data centers and stations, communication light transmitted through a communication optical fiber is often invisible light outside the visible light range. This means that the user cannot visually check the state of communication in the communication optical fiber.
Therefore, the communication optical fiber in use may be erroneously identified as not being in use, and an optical connector optically connected to the middle of the communication optical fiber may be removed by mistake. This may lead to serious failures in communication.
Techniques have been developed, which are capable of detecting the presence of communication light transmitted through a communication optical fiber without interrupting the communication, and are capable of enabling the user to visually check the state of communication in the communication optical fiber.
For example, there is a proposed technique in which a light transmissive resin, such as a refractive index matching agent, is charged into a gap in the middle of a communication optical fiber. Part of communication light scattered by the light transmissive resin is detected as leakage light by a light receiving element or the like, and the detected leakage light is converted to visible light. This enables the user to visually check the state of communication (see, e.g., Japanese Patent No. 4927028).
However, the amount of leakage light may be changed by entry of air bubbles during charging of the light transmissive resin, or by changes in refractive index of the light transmissive resin with changing environmental temperature. This results in significant product-to-product variations, and it is difficult to maintain a stable amount of leakage light over a long period of time.